Core 4: Computation Summary The Computation Core provides both a service component (helping CRNA projects to make effective use of up-to-date tools in structure exploration, refinement, NMR analysis, and sequence analysis), and as a focus for technology development and technology transfer (especially in the areas of NMR structure determination, SAXS reconstructions, and sequence analysis). The technology development and transfer work focuses on three main areas: (i) using up-to-date molecular dynamics simulation methods and force fields to assist in structure determination based on crystallography, SAXS and cryo-EM data with a key emphasis on the development of novel ways to interpret small-angle X-ray scattering (SAXS) data and to combine this information with restraints derived from NMR, (ii) developing and supporting integrated tools for NMR spectrum analysis and structure generation and refinement with a key focus on creating novel tools to make use of chemical shifts in RNA structure analysis and refinement, and (iii) investigating the evolution of functional RNA sequences in the HIV-1 genome through analysis of nucleotide sequence data, which will lead to novel bioinformatics methods for identifying functional RNA elements in viral genomes, and the creation of a web resource to support these analyses for HIV-1.